Fin field-effect transistor device and method

ABSTRACT

A method includes removing a first portion of a dummy gate structure over a first fin while keeping a second portion of the dummy gate structure over a second fin, where removing the first portion forms a first recess exposing the first fin, forming a first gate dielectric material in the first recess and over the first fin, and removing the second portion of the dummy gate structure over the second fin, where removing the second portion forms a second recess exposing the second fin. The method further includes forming a second gate dielectric material in the second recess and over the second fin, the second gate dielectric material contacting the first gate dielectric material, and filling the first recess and the second recess with a conductive material.

BACKGROUND

The semiconductor industry has experienced rapid growth due tocontinuous improvements in the integration density of a variety ofelectronic components (e.g., transistors, diodes, resistors, capacitors,etc.). For the most part, this improvement in integration density hascome from repeated reductions in minimum feature size, which allows morecomponents to be integrated into a given area.

Fin Field-Effect Transistor (FinFET) devices are becoming commonly usedin integrated circuits. FinFET devices have a three-dimensionalstructure that comprises a semiconductor fin protruding from asubstrate. A gate structure, configured to control the flow of chargecarriers within a conductive channel of the FinFET device, wraps aroundthe semiconductor fin. For example, in a tri-gate FinFET device, thegate structure wraps around three sides of the semiconductor fin,thereby forming conductive channels on three sides of the semiconductorfin.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a perspective view of a Fin Field-Effect Transistor(FinFET) device, in accordance with some embodiments.

FIGS. 1-6, 7A, 7B, 7C, 7D, and 8-21 illustrate cross-sectional views ofa FinFET device at various stages of fabrication, in accordance withsome embodiments.

FIG. 22 illustrates a flow chart of method of making a semiconductordevice, in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the invention. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Embodiments of the present disclosure are discussed in the context offorming a FinFET device, and in particular, in the context of formingreplacement gates of a FinFET device. In accordance with someembodiments, a dummy gate over a first fin and over a second fin isreplaced by a first gate structure over the first fin and a second gatestructure over the second fin. The first gate structure contacts thesecond gate structure, with the gate dielectric material of the firstgate structure and the gate dielectric material of the second gatestructure disposed between the two gate structures and forming aninsulation region between the two gate structures. A small fin-to-finpitch is achieved due to the insulation region formed by the gatedielectric materials.

FIG. 1 illustrates an example of a FinFET 30 in a perspective view. TheFinFET 30 includes a substrate 32 having a fin 36. The substrate 32 hasisolation regions 34 formed thereon, and the fin 36 protrudes above andbetween neighboring isolation regions 34. A gate dielectric 38 is alongsidewalls and over a top surface of the fin 36, and a gate electrode 40is over the gate dielectric 38. Source/drain regions 42 and 44 are inthe fin on opposite sides of the gate dielectric 38 and gate electrode40. FIG. 1 further illustrates reference cross-sections that are used inlater figures. Cross-section B-B extends along a longitudinal axis ofthe gate electrode 40 of the FinFET 30. Cross-section A-A isperpendicular to cross-section B-B and is along a longitudinal axis ofthe fin 36 and in a direction of, for example, a current flow betweenthe source/drain regions 42 and 44. Cross-section C-C is parallel tocross-section B-B and is across the source/drain region 42. Subsequentfigures refer to these reference cross-sections for clarity.

FIGS. 2-21 are cross-sectional views of a FinFET device 100 at variousstages of fabrication in accordance with an embodiment. The FinFETdevice 100 is similar to the FinFET 30 in FIG. 1, except for multiplefins. FIGS. 2-5 illustrate cross-section views of a FinFET device 100along cross-section B-B. FIGS. 6 and 7A illustrate cross-section viewsof the FinFET device 100 along cross-section A-A, FIG. 7B illustrate across-section view of the FinFET device 100 along cross-section B-B, andFIGS. 7C and 7D illustrate cross-section views of the FinFET device 100along cross-section C-C. FIGS. 8-21 illustrate cross-section views ofthe FinFET device 100 along cross-section B-B.

FIG. 2 illustrates a cross-sectional view of a substrate 50. Thesubstrate 50 may be a semiconductor substrate, such as a bulksemiconductor, a semiconductor-on-insulator (SOI) substrate, or thelike, which may be doped (e.g., with a p-type or an n-type dopant) orundoped. The substrate 50 may be a wafer, such as a silicon wafer.Generally, an SOI substrate includes a layer of a semiconductor materialformed on an insulator layer. The insulator layer may be, for example, aburied oxide (BOX) layer, a silicon oxide layer, or the like. Theinsulator layer is provided on a substrate, typically a silicon or glasssubstrate. Other substrates, such as a multi-layered or gradientsubstrate may also be used. In some embodiments, the semiconductormaterial of the substrate 50 may include silicon; germanium; a compoundsemiconductor including silicon carbide, gallium arsenic, galliumphosphide, indium phosphide, indium arsenide, and/or indium antimonide;an alloy semiconductor including SiGe, GaAsP, AlInAs, AlGaAs, GaInAs,GaInP, and/or GaInAsP; or combinations thereof.

As illustrated in FIG. 2, the substrate includes a first portion inregion 200, and a second portion in region 300. The first portion of thesubstrate 50 in region 200 may be used to form P-type devices such asP-type metal-oxide-semiconductor field-effect transistors (MOSFETs), andthe second portion of the substrate 50 in region 300 may be used to formN-type devices such as N-type MOSFETs. Therefore, the region 200 may bereferred to as a PMOS region, and the region 300 may be referred to asan NMOS region in some embodiments. In other embodiments, both region200 and region 300 are PMOS regions or NMOS regions.

Referring to FIG. 3, the substrate 50 shown in FIG. 2 is patternedusing, for example, photolithography and etching techniques. Forexample, a mask layer, such as a pad oxide layer 52 and an overlying padnitride layer 56, is formed over the substrate 50. The pad oxide layer52 may be a thin film comprising silicon oxide formed, for example,using a thermal oxidation process. The pad oxide layer 52 may act as anadhesion layer between the substrate 50 and the overlying pad nitridelayer 56 and may act as an etch stop layer for etching the pad nitridelayer 56. In some embodiments, the pad nitride layer 56 is formed ofsilicon nitride, silicon oxynitride, silicon carbide, siliconcarbonitride, the like, or a combination thereof, and may be formedusing low-pressure chemical vapor deposition (LPCVD) or plasma enhancedchemical vapor deposition (PECVD), as examples.

The mask layer may be patterned using photolithography techniques.Generally, photolithography techniques utilize a photoresist material(not shown) that is deposited, irradiated (exposed), and developed toremove a portion of the photoresist material. The remaining photoresistmaterial protects the underlying material, such as the mask layer inthis example, from subsequent processing steps, such as etching. In thisexample, the photoresist material is used to pattern the pad oxide layer52 and pad nitride 56 to form a patterned mask 58, as illustrated inFIG. 3.

The patterned mask 58 is subsequently used to pattern exposed portionsof the substrate 50 to form trenches 61, thereby defining semiconductorfins 64 (e.g., fin 64A in region 200, and fin 64B in region 300) betweenadjacent trenches 61 as illustrated in FIG. 3. In some embodiments, thesemiconductor fins 64 are formed by etching trenches in the substrate 50using, for example, reactive ion etch (RIE), neutral beam etch (NBE),the like, or a combination thereof. The etch may be anisotropic. In someembodiments, the trenches 61 may be strips (viewed from in the top)parallel to each other, and closely spaced with respect to each other.In some embodiments, the trenches 61 may be continuous and surround thesemiconductor fins 64.

The fins 64 may be patterned by any suitable method. For example, thefins may 64 be patterned using one or more photolithography processes,including double-patterning or multi-patterning processes. Generally,double-patterning or multi-patterning processes combine photolithographyand self-aligned processes, allowing patterns to be created that have,for example, pitches smaller than what is otherwise obtainable using asingle, direct photolithography process. For example, in one embodiment,a sacrificial layer is formed over a substrate and patterned using aphotolithography process. Spacers are formed alongside the patternedsacrificial layer using a self-aligned process. The sacrificial layer isthen removed, and the remaining spacers, or mandrels, may then be usedto pattern the fins.

FIG. 4 illustrates the formation of an insulation material betweenneighboring semiconductor fins 64 to form isolation regions 62. Theinsulation material may be an oxide, such as silicon oxide, a nitride,the like, or a combination thereof, and may be formed by a high densityplasma chemical vapor deposition (HDP-CVD), a flowable CVD (FCVD) (e.g.,a CVD-based material deposition in a remote plasma system and postcuring to make it convert to another material, such as an oxide), thelike, or a combination thereof. Other insulation materials and/or otherformation processes may be used. In the illustrated embodiment, theinsulation material is silicon oxide formed by a FCVD process. An annealprocess may be performed once the insulation material is formed. Aplanarization process, such as a chemical mechanical polish (CMP), mayremove any excess insulation material and form top surfaces of theisolation regions 62 and top surfaces of the semiconductor fins 64 thatare coplanar (not shown). The patterned mask layer 58 (see FIG. 3) mayalso be removed by the planarization process.

In some embodiments, the isolation regions 62 include a liner, e.g., aliner oxide (not shown), at the interface between the isolation region62 and the substrate 50/semiconductor fins 64. In some embodiments, theliner oxide is formed to reduce crystalline defects at the interfacebetween the substrate 50 and the isolation region 62. Similarly, theliner oxide may also be used to reduce crystalline defects at theinterface between the semiconductor fins 64 and the isolation region 62.The liner oxide (e.g., silicon oxide) may be a thermal oxide formedthrough a thermal oxidation of a surface layer of substrate 50, althoughother suitable method may also be used to form the liner oxide.

Next, the isolation regions 62 are recessed to form shallow trenchisolation (STI) regions 62. The isolation regions 62 are recessed suchthat the upper portions of the semiconductor fins 64 protrude frombetween neighboring STI regions 62. The top surfaces of the STI regions62 may have a flat surface (as illustrated), a convex surface, a concavesurface (such as dishing), or a combination thereof. The top surfaces ofthe STI regions 62 may be formed flat, convex, and/or concave by anappropriate etch. The isolation regions 62 may be recessed using anacceptable etching process, such as one that is selective to thematerial of the isolation regions 62. For example, a chemical oxideremoval using a CERTAS® etch or an Applied Materials SICONI tool ordilute hydrofluoric (dHF) acid may be used.

FIGS. 2 through 4 illustrate an embodiment of forming fins 64, but finsmay be formed in various different processes. In one example, adielectric layer can be formed over a top surface of a substrate;trenches can be etched through the dielectric layer; homoepitaxialstructures can be epitaxially grown in the trenches; and the dielectriclayer can be recessed such that the homoepitaxial structures protrudefrom the dielectric layer to form fins. In another example,heteroepitaxial structures can be used for the fins. For example, thesemiconductor fins can be recessed, and a material different from thesemiconductor fins may be epitaxially grown in their place.

In an even further example, a dielectric layer can be formed over a topsurface of a substrate; trenches can be etched through the dielectriclayer; heteroepitaxial structures can be epitaxially grown in thetrenches using a material different from the substrate; and thedielectric layer can be recessed such that the heteroepitaxialstructures protrude from the dielectric layer to form fins.

In some embodiments where homoepitaxial or heteroepitaxial structuresare epitaxially grown, the grown materials may be in situ doped duringgrowth, which may obviate prior and subsequent implantations although insitu and implantation doping may be used together. Still further, it maybe advantageous to epitaxially grow a material in an NMOS regiondifferent from the material in a PMOS region. In various embodiments,the fins may comprise silicon germanium (SixGe1−x, where x can bebetween 0 and 1), silicon carbide, pure or substantially pure germanium,a III-V compound semiconductor, a II-VI compound semiconductor, or thelike. For example, the available materials for forming III-V compoundsemiconductor include, but are not limited to, InAs, AlAs, GaAs, InP,GaN, InGaAs, InAlAs, GaSb, AlSb, AlP, GaP, and the like.

FIG. 5 illustrates the formation of dummy gate structure 75 over thesemiconductor fins 64. Dummy gate structure 75 includes gate dielectric66 and gate 68, in some embodiments. A mask 70 may be formed over thedummy gate structure 75. To form the dummy gate structure 75, adielectric layer is formed on the semiconductor fins 64. The dielectriclayer may be, for example, silicon oxide, silicon nitride, multilayersthereof, or the like, and may be deposited or thermally grown accordingto acceptable techniques.

A gate layer is formed over the dielectric layer, and a mask layer isformed over the gate layer. The gate layer may be deposited over thedielectric layer and then planarized, such as by a CMP. The mask layermay be deposited over the gate layer. The gate layer may be formed of,for example, polysilicon, although other materials may also be used. Insome embodiments, the gate layer may include a metal-containing materialsuch as TiN, TaN, TaC, Co, Ru, Al, combinations thereof, or multi-layersthereof. The mask layer may be formed of, for example, silicon nitrideor the like.

After the layers (e.g., the dielectric layer, the gate layer, and themask layer) are formed, the mask layer may be patterned using acceptablephotolithography and etching techniques to form mask 70. The pattern ofthe mask 70 then may be transferred to the gate layer and the dielectriclayer by an acceptable etching technique to form gate 68 and gatedielectric 66, respectively. The gate 68 and the gate dielectric 66cover respective channel regions of the semiconductor fins 64. The gate68 may also have a lengthwise direction substantially perpendicular tothe lengthwise direction of respective semiconductor fins 64.

The gate dielectric 66 is shown to be formed over the top surfaces andsidewalls of the fins 64 in the example of FIG. 5. In other embodiments,the gate dielectric 66 may be formed over the fins 64 and over the STIregions 62, e.g., the gate dielectric 66 may extends continuously fromthe fin 64A to the fin 64B. These and other variations are fullyintended to be included within the scope of the present disclosure.

FIGS. 6 and 7A illustrate the cross-section views of further processingof the FinFET device 100 along cross-section A-A (along a longitudinalaxis of the fin 64). The processing illustrated in FIGS. 6 and 7A areperformed for both the region 200 (e.g., a PMOS region) and the region300 (e.g., an NMOS region), in some embodiments. Therefore, onecross-sectional view along cross-section A-A of the fin 64A or 64B(instead of two cross-sectional views along cross-section A-A of the fin64A and along cross-section A-A of the fin 64B), is shown in each ofFIGS. 6 and 7A.

As illustrated in FIG. 6, lightly doped drain (LDD) regions 65 areformed in the fins 64. The LDD regions 65 may be formed by a plasmadoping process. The plasma doping process may include forming andpatterning masks such as a photoresist to cover the regions of theFinFET that are to be protected from the plasma doping process. Theplasma doping process may implant N-type or P-type impurities in thefins 64 to form the LDD regions 65. For example, P-type impurities, suchas boron, may be implanted in the fin 64A to form the LDD regions 65 fora P-type device, and N-type impurities, such as phosphorus, may beimplanted in the fin 64B to form the LDD regions 65 for an N-typedevice. In some embodiments, the LDD regions 65 abut the channel regionof the FinFET device 100. Portions of the LDD regions 65 may extendunder gate 68 and into the channel region of the FinFET device 100. FIG.6 illustrates a non-limiting example of the LDD regions 65. Otherconfigurations, shapes, and formation methods of the LDD regions 65 arealso possible and are fully intended to be included within the scope ofthe present disclosure. For example, LDD regions 65 may be formed afterfirst gate spacers 72 are formed.

Still referring to FIG. 6, after the LDD regions 65 are formed, a gatespacer 87 is formed on the gate structure. The gate spacer 87 mayinclude a first gate spacer 72 and a second gate spacer 86. In theexample of FIG. 6, the first gate spacer 72 is formed on opposingsidewalls of the gate 68 and on opposing sidewalls of the gatedielectric 66. The second gate spacer 86 is formed on the first gatespacer 72, as illustrated in FIG. 6. The first gate spacer 72 may beformed of a nitride, such as silicon nitride, silicon oxynitride,silicon carbide, silicon carbonitride, the like, or a combinationthereof, and may be formed using, e.g., a thermal oxidation, CVD, orother suitable deposition process. The second gate spacer 86 may beformed of silicon nitride, SiCN, a combination thereof, or the likeusing a suitable deposition method.

In an exemplary embodiment, the gate spacer 87 is formed by firstconformally depositing a conformal first gate spacer layer over theFinFET device 100, then conformally depositing a second gate spacerlayer over the deposited first gate spacer layer. Next, an anisotropicetch process, such as a dry etch process, is performed to remove a firstportion of the second gate spacer layer disposed on upper surfaces ofthe FinFET device 100 (e.g., the upper surface of the mask 70) whilekeeping a second portion of the second gate spacer layer disposed alongsidewalls of the gate structure. The second portion of the second gatespacer layer remaining after the anisotropic etch process forms thesecond gate spacer 86. The anisotropic etch process also removes aportion of the first gate spacer layer disposed outside of the sidewallsof the second gate spacer 86, and the remaining portion of the firstgate spacer layer forms the first gate spacer 72.

The shapes and formation methods of the first gate spacer 72 and thesecond gate spacer 86 as illustrated in FIG. 6 are merely non-limitingexamples, and other shapes and formation methods are possible. Forexample, the second gate spacers 86 may be formed after the epitaxialsource/drain regions 80 (see FIG. 7A) are formed. These and othervariations are fully intended to be included within the scope of thepresent disclosure.

Next, as illustrated in FIG. 7A, source/drain regions 80 are formed. Thesource/drain regions 80 are formed by etching the fins 64 to formrecesses, and epitaxially growing a material in the recess, usingsuitable methods such as metal-organic CVD (MOCVD), molecular beamepitaxy (MBE), liquid phase epitaxy (LPE), vapor phase epitaxy (VPE),selective epitaxial growth (SEG), the like, or a combination thereof.

As illustrated in FIG. 7A, the epitaxial source/drain regions 80 mayhave surfaces raised from respective surfaces of the fins 64 (e.g.raised above the non-recessed portions of the fins 64) and may havefacets. The source/drain regions 80 of the adjacent fins 64 may merge toform a continuous epitaxial source/drain region 80 (see FIG. 7C). Insome embodiments, the source/drain regions 80 for adjacent fins 64 donot merge together and remain separate source/drain regions 80 (see FIG.7D). In some embodiments, the resulting FinFET in region 300 (e.g., anNMOS region) is an n-type FinFET, and source/drain regions 80 of the fin64B comprise silicon carbide (SiC), silicon phosphorous (SiP),phosphorous-doped silicon carbon (SiCP), or the like. In someembodiments, the resulting FinFET in region 200 (e.g., a PMOS region) isa p-type FinFET, and source/drain regions 80 of the fin 64A compriseSiGe, and a p-type impurity such as boron or indium.

The epitaxial source/drain regions 80 may be implanted with dopants toform source/drain regions 80 followed by an anneal process. Theimplanting process may include forming and patterning masks such as aphotoresist to cover the regions of the FinFET that are to be protectedfrom the implanting process. The source/drain regions 80 may have animpurity (e.g., dopant) concentration in a range from about 1E19 cm−3 toabout 1E21 cm−3. P-type impurities, such as boron or indium, may beimplanted in the source/drain region 80 of a P-type transistor (e.g., inthe region 200). N-type impurities, such as phosphorous or arsenide, maybe implanted in the source/drain regions 80 of an N-type transistor(e.g., in the region 300). In some embodiments, the epitaxialsource/drain regions may be in situ doped during growth.

As illustrated in FIG. 7A, a first interlayer dielectric (ILD) 90 isformed over the source/drain regions 80, the fins 64, and the dummy gatestructures 75. In some embodiments, the first ILD 90 is formed of adielectric material such as phosphosilicate glass (PSG), borosilicateglass (BSG), boron-doped phosphosilicate Glass (BPSG), undoped silicateglass (USG), or the like, and may be deposited by any suitable method,such as CVD, PECVD, or FCVD. A planarization process, such as a CMPprocess, may be performed to remove the mask 70, and to planarize thetop surface of the first ILD 90 such that the top surface of the firstILD 90 is level with the top surface of the gate 68.

FIG. 7B illustrates the cross-sectional view of the FinFET device 100shown in FIG. 7A, but along cross-section B-B. As illustrated in FIG.7B, the gate 68 is disposed over the fin 64A and the fin 64B, andextends continuously from the fin 64A in region 200 (e.g., a PMOSregion) to the fin 64B in region 300 (e.g., an NMOS region). Althoughnot illustrated in FIG. 7B, the gate spacer 87 (see FIG. 6) may beformed between the gate 68 and the first ILD 90. An embodiment gate-lastprocess (sometimes referred to as replacement gate process) is performedsubsequently to replace the gate 68 and the gate dielectric 66 withactive gates and active gate dielectric materials. Therefore, the gate68 and the gate dielectric 66 are considered dummy gate structures in agate-last process. The embodiment gate-last process, once finished,replaces the dummy gate structure with two gate structures that contacteach other. Details of the embodiment gate-last process is describedhereinafter with reference to FIGS. 8-21.

FIG. 7C illustrates a cross-sectional view of the FinFET device 100shown in FIG. 7A, but along cross-section C-C, in accordance with anembodiment. In the example of FIG. 7C, the source/drain regions 80A overthe fin 64A merge with the source/drain regions 80B over the fin 64B toform a continuous source/drain region 80 over the fins 64A and 64B. FIG.7C also illustrates spacers 86′ on opposing sidewalls of thesource/drain regions 80A/80B, which spacers 86′ may be formed of a samematerial as the material of the second gate spacer 86.

FIG. 7D illustrates a cross-sectional view of the FinFET device 100shown in FIG. 7A, but along cross-section C-C, in accordance withanother embodiment. In the example of FIG. 7D, the source/drain regions80A over the fin 64A are separate from, thus do not merge with, thesource/drain regions 80B over the fin 64B. FIG. 7D also illustratesspacers 86′ on opposing sidewalls of the source/drain regions 80A/80B,which spacers 86′ may be formed of a same material as the material ofthe second gate spacer 86.

FIGS. 8-21 illustrates cross-sectional views of the FinFET device 100along cross-section B-B during further processing, in accordance withsome embodiments. Referring to FIG. 8, a hard mask layer 73 is formedover the gate 68 and the first ILD 90. The hard mask layer 73 maycomprise silicon oxide, silicon nitride, silicon carbon nitride, or thelike, and may be formed by physical vapor deposition (PVD), chemicalvapor deposition (CVD), atomic layer deposition (ALD), or other suitabledeposition method. Next, a photo sensitive layer 71, such as aphotoresist, is formed over the hard mask layer 73. The photo sensitivelayer 71 is then patterned, e.g., using photolithography and/or etchingtechniques, to expose a portion of the hard mask layer 73 over theregion 200 while covering a portion of the hard mask layer 73 over theregion 300, as illustrated in FIG. 8.

Next, in FIG. 9, the patterns of the patterned photo sensitive layer 71is transferred to the hard mask layer 73 using a suitable process suchas an anisotropic etching process. The photo sensitive layer 71 is thenremoved using, e.g., an ashing process or any suitable removal process.The patterned hard mask layer 73 is used to shield a portion of thedummy gate structures (e.g., the gate 68 and the gate dielectric 66) inthe region 300 from a subsequent etching process.

Next, a portion of the gate 68 in the region 200 is removed to form arecess 77, which recess 77 exposes the gate dielectric 66 and the fin64A. In some embodiments, the gate 68 in the region 200 is removed by ananisotropic etching process such as a plasma etching process. In anexemplary embodiment, the anisotropic etching process (e.g., a plasmaetching process) is performed as a two-step process that includes afirst etching step using a first etching gas, followed by a secondetching step using a second etching gas different from the first etchinggas. For example, the first etching step may be performed using thefirst etching gas comprising HBr and NF₃, and the second etching stepmay be performed using the second etching gas comprising Cl₂ and O₂. Thefirst etching allows for control of the vertical profile of the recess77 and better control of the critical dimension (CD) of the FinFETdevice 100, and the second etching process offers etching selectivitybetween the material of the gate 68 and the material(s) of theunderlying layer(s) of the gate 68, in some embodiments.

In some embodiments, during the first etching step, a flow rate of HBris in a range from about 100 standard cubic centimeter per minute (sccm)to about 1000 sccm, and a flow rate of NF₃ is in a range from about 100sccm to about 1000 sccm. A temperature of the first etching step is in arange from about 20° C. to about 100° C. The first etching step may beperformed to remove the upper half of the gate 68 in the region 200, andthe second etching step may then be performed to remove the remaininglower half of the gate 68 in the region 200.

In some embodiments, during the second etching step, a flow rate of Cl₂is in a range from about 100 sccm to about 1000 sccm, and a flow rate ofO₂ is in a range from about 100 sccm to about 1000 sccm. A temperatureof the second etching step is in a range from about 20° C. to about 100°C. As illustrated in FIG. 9, the gate 68 in the region 200 is removedafter the second etching step, and the recess 77 exposes the STI regions62 and the gate dielectric 66 over the fin 64A.

Referring to FIG. 10, the gate dielectric 66 (e.g., silicon oxide) overthe fin 64A is removed using, e.g., dry etch, wet etch, or any suitableremoval process. In some embodiments, the gate dielectric 66 over thefin 64A is removed by a chemical etching process using HF as theetchant. As illustrated in FIG. 10, an upper surface and sidewalls ofthe fin 64A are exposed by the recess 77.

Referring next to FIG. 11, a gate dielectric material 81 is conformallyformed in the recess 77, over the upper surface of the first ILD 90, andover the upper surface of the hard mask layer 73. As illustrated in FIG.11, the gate dielectric material 81 lines the bottom and sidewalls ofthe recess 77 (see FIG. 10). The gate dielectric material 81 also linesthe upper surface and the sidewalls of the fin 64, and the upper surfaceof the STI region 62. The gate dielectric material 81 may includesilicon dioxide. The silicon oxide may be formed by suitable oxidationand/or deposition methods. In some embodiments, the gate dielectricmaterial 81 includes a high-k dielectric layer such as hafnium oxide(HfO₂). Alternatively, the high-k dielectric layer may optionallyinclude other high-k dielectrics, such as TiO₂, HfZrO, Ta₂O₃, HfSiO₄,ZrO₂, ZrSiO₂, combinations thereof, or other suitable material. Thehigh-k dielectric layer may be formed by ALD, PVD, CVD, or othersuitable methods.

As illustrated in FIG. 11, a capping layer 83 is conformally formed overthe gate dielectric material 81. The capping layer 83 may act as aprotection layer for the gate dielectric material 81. In someembodiments, the capping layer 83 comprises TiN, TiSiN, TaN, LaO, TiAl,TaAl, TiAlC, or TaAlC, and is formed by ALD, PVD, CVD, or other suitablemethods.

Next, a barrier layer 85 is conformally formed over the capping layer83. The barrier layer 85 may prevent or reduce the out diffusion of thematerial of a subsequently formed gate electrode (see, e.g., 88A and 88Bin FIG. 19). The barrier layer 85 may also function as an etch stoplayer to control a subsequent etching process. The barrier layer 85 maycomprise a conductive material such as titanium nitride, although othermaterials, such as tantalum nitride, titanium, tantalum, or the like mayalternatively be utilized. The barrier layer 85 may be formed using aCVD process, such as plasma-enhanced CVD (PECVD). However, otheralternative processes, such as sputtering or metal organic chemicalvapor deposition (MOCVD), ALD, may alternatively be used. In anexemplary embodiment, the capping layer 83 comprises titanium nitride(TiN), and the barrier layer 85 comprises tantalum nitride (TaN).

Next, a sacrificial material 89 is formed in the recess 77 and over thebarrier layer 85. The sacrificial material 89 may fill and overfill therecess 77, as illustrated in FIG. 11. The sacrificial material 89 may beany suitable material that provides an etch selectivity over itsunderlying layer (e.g., barrier layer 85), and that may be removedeasily by an etching process. In some embodiments, the sacrificialmaterial 89 comprise a metal. In an exemplary embodiment, thesacrificial material 89 comprises an alloy, such as an alloy of aluminumand copper (e.g., AlCu), and is formed by PVD, CVD, plating, or anysuitable deposition method. Besides AlCu, other suitable material, suchas tungsten (W), or an organic bottom anti-reflective coating (BARC)material, may also be used for the sacrificial material 89.

Next, in FIG. 12, a planarization process, such as CMP, is performed toremove excess portions of the sacrificial material 89 outside of therecess 77. The planarization process also removes the hard mask layer73, and portions of the gate dielectric material 81/capping layer83/barrier layer 85 over the upper surface of the first ILD 90 (e.g., inthe region 300). After the planarization process, the gate 68 over thefin 64B in the region 300 is exposed. In the illustrated example of FIG.12, portions of the gate dielectric material 81/capping layer 83/barrierlayer 85 over the upper surface of the first ILD 90 in the first region200 remain after the planarization process, because the upper surface ofthe ILD 90 in the region 200 is lower than the upper surface of the ILD90 in the region 300 at this stage of processing.

Referring now to FIG. 13, the portion of the gate 68 over the fin 64B(e.g., the portion of the gate 68 in the region 300) is removed. In someembodiments, an isotropic etching process is performed to remove thegate 68. In an exemplary embodiment, an etchant of the isotropic etchingprocess is selective to the material of the gate 68 (e.g., having ahigher etching rate for the material of the gate 68 than other exposedmaterials), thus no mask is needed to cover the features formed in theregion 200 during the isotropic etching process. For example, a wet etchusing NH₄OH may be performed to remove the gate 68. Other suitableetching process, such as a dry etch, may also be used. After the removalof the portion of the gate 68 over the fin 64B in FIG. 13, a recess 79is formed, which recess 79 exposes a sidewall portion 81S of the gatedielectric material 81 and the gate dielectric 66 on the fin 64B, whichsidewall portion 81S was in contact with a sidewall of the portion ofthe gate 68 over the fin 64B before that portion of the gate 68 wasremoved.

Next, in FIG. 14, the gate dielectric 66 over the fin 64B is removed,e.g., using dry etch, wet etch, or any suitable removal process. In someembodiments, the gate dielectric 66 over the fin 64B is removed by achemical etching process using HF as the etchant. As illustrated in FIG.14, an upper surface and sidewalls of the fin 64B are exposed by therecess 79.

In FIG. 15, a gate dielectric material 81′, a capping layer 83′, and abarrier 85′ are formed successively over the FinFET device 100 shown inFIG. 14, and a sacrificial material 89′ is formed to fill and overfillthe recess 79. As illustrated in FIG. 15, the gate dielectric material81′, the capping layer 83′, and the barrier 85′ are conformal to theirrespective underlying layer(s). The materials and the formation methodsfor the gate dielectric material 81′, the capping layer 83′, the barrierlayer 85′, and the sacrificial material 89′ may be similar to those ofthe gate dielectric material 81, the capping layer 83, the barrier layer85, and the sacrificial material 89, respectively, although in someembodiments, the material(s) of certain layer(s) (e.g., the gatedielectric material 81′) may be adjusted for the type of devices (e.g.,N-type devices) to be formed in the region 300, and thus, may bedifferent from the corresponding material(s) in the region 200.

As illustrated in FIG. 15, the gate dielectric material 81′ physicallycontacts and extends along the sidewall portion 81S (see FIG. 14) of thegate dielectric material 81. Therefore, at the boundary between theregion 200 and the region 300, the gate dielectric material 81 and thegate dielectric material 81′ form an insulation region, which insulationregion separates the subsequently formed gate electrode 88A (see FIG.19) from the subsequently formed gate electrode 88B (see FIG. 19). Inembodiments where the gate dielectric material 81 and the gatedielectric material 81′ comprise a same material (e.g., a same high-Kdielectric material), the same material extends continuously from thefin 64A to the fin 64B.

Since the gate dielectric material 81′/capping layer 83′/barrier layer85′ are conformally formed over the upper surface of the sacrificialmaterial 89, the sacrificial material 89 is surrounded by a combinationof the layer stack 81/83/85 and the layer stack 81′/83′/85′. Forexample, the sacrificial material 89 is disposed between the layer stack81/83/85 and the layer stack 81′/83′/85′ along the horizontal directionand along the vertical direction, as illustrated in FIG. 15.

Next, as illustrated in FIG. 16, a planarization process, such as CMP,is performed to remove portions of the deposited layers (e.g., 81/83/85,89, 81′/83′/85′, and 89′) that are over the upper surface of the firstILD 90. After the planarization process, the sacrificial material 89,the sacrificial material 89′, and the first ILD 90 have a coplanar uppersurface. As shown in FIG. 16, a sidewall portion 81'S of the gatedielectric material 81′ extends along and contacts the sidewall portion81S of the gate dielectric material 81.

Referring to FIG. 17, the sacrificial materials 89 and 89′ are removedto form recesses 77′ and 79′. An isotropic etching process, such as awet clean, is performed to remove the sacrificial materials 89 and 89′,in some embodiments. The isotropic etching process may selectivelyremove the sacrificial materials 89 and 89′. For example, a wet cleanusing hydrofluoric acid (HF), diluted tris-borate-ethylene diaminetetraacetic acid (TBE), or other suitable etchant may be performed toremove the sacrificial materials 89 and 89′.

Next, as illustrated in FIG. 18, a conductive material 88 is formed tofill the recesses 77′ and 79′ to form the gate structures of the FinFETdevice 100. the conductive material 88 may be formed onto a seed layer(not shown) over the barrier layers 85/85′. The seed layer may includecopper (Cu), titanium (Ti), tantalum (Ta), titanium nitride (TiN),tantalum nitride (TaN), the like, or a combination thereof, and may bedeposited by atomic layer deposition (ALD), sputtering, physical vapordeposition (PVD), or the like. The conductive material 88 may comprisetungsten, although other suitable materials such as aluminum, copper,rhuthenium, silver, gold, rhodium, molybdenum, nickel, cobalt, cadmium,zinc, alloys of these, combinations thereof, and the like, mayalternatively be utilized. The conductive material 88 may be formed byelectroplating, PVD, CVD, or any suitable deposition method.

Although not illustrated in FIG. 18, different work function layers suchas P-type work function layers and N-type work function layers may beformed in the recesses 77′ and 79′, respectively, over the barrierlayers 85/85′ and before the conductive material 88 is formed, in someembodiments. Patterned mask layer(s) may be formed to shield one region(e.g., region 300) while the work function layer for another region(e.g., region 200) is being formed. Exemplary p-type work functionmetals that may be included in the gate structure include TiN, TaN, Ru,Mo, Al, WN, ZrSi₂, MoSi₂, TaSi₂, NiSi₂, WN, other suitable p-type workfunction materials, or combinations thereof. Exemplary n-type workfunction metals that may be included in the gate structure include Ti,Ag, TaAl, TaAlC, TiAIN, TaC, TaCN, TaSiN, Mn, Zr, other suitable n-typework function materials, or combinations thereof. A work function valueis associated with the material composition of the work function layer,and thus, the material of the work function layer is chosen to tune itswork function value so that a target threshold voltage Vt is achieved inthe device that is to be formed in the respective region (e.g., theregions 200 and 300). The work function layer(s) may be deposited byCVD, physical vapor deposition (PVD), and/or other suitable process.

Next, in FIG. 19, a planarization process, such as CMP, is performed toremove portions of the conductive material 88 over the upper surface ofthe first ILD 90. After the planarization process, gate electrodes 88Aand 88B are formed in the region 200 and the region 300, respectively.The layer stack 81/83/85 and the gate electrode 88A therefore form agate structure 84A in the region 200, and the layer stack 81′/83′/85′and the gate electrode 88B therefore form a gate structure 84B in theregion 300. In some embodiments, the gate structure 84A is the gatestructure of a P-type FinFET transistor, and the gate structure 84B isthe gate structure of an N-type transistor. The gate structure 84Acontacts the gate structure 84B, as illustrated in FIG. 19. Inparticular, the gate dielectric material 81 (e.g., the sidewall portion81S) of the gate structure 84A contacts the gate dielectric material 81′(e.g., the sidewall portion 81'S) of the gate structure 84B. Asillustrated in FIG. 19, the gate structure 84A and the gate structure84B are insulated from each other by the gate dielectric materials 81and 81′. The gate structure 84A and 84B may be controlled independentlyby two voltages, e.g., a first voltage and a second voltage which may bedifferent from the first voltage, in some embodiments.

As illustrated in FIG. 19, the sidewall portion 81S of the gatedielectric material 81 extends along a sidewall of the gate electrode88A. Similarly, the sidewall portion 81'S of the gate dielectricmaterial 81′ extends along a sidewall of the gate electrode 88B. Thesidewall portion 81S and the sidewall portion 81S′ have a same heightmeasured along a direction of the sidewalls of the gate electrodes 88Aand 88B, e.g., along a direction perpendicular to an upper surface ofthe STI region 62. The sidewall portion 81S and the sidewall portion81′S form an insulation region that insulates the gate electrode 88Afrom the gate electrode 88B. In the illustrated example of FIG. 19, theinsulation region is substantially perpendicular to portions of the gatedielectric materials 81 and 81′ that extend along the upper surface ofthe STI region 62.

FIG. 20 shows a zoomed-in view of an area 410 of FIG. 19. As illustratedin FIG. 20, the gate dielectric materials 81 and 81′ form an insulationregion between the gate structures 84A and 84B. In the example of FIG.20, a thickness D₁ of the insulation region, which is equal to a sum ofthe thicknesses of the gate dielectric materials 81 and 81′, is betweenabout 1.5 nm and about 6 nm, such as about 3 nm. A distance D₂ from thefin 64A to the insulation region is in a range from about 10 nm to about30 nm, such as about 21.5 nm, and a distance D₃ from the fin 64B to theinsulation region is in a range from about 10 nm to about 30 nm, such asabout 21.5 nm. Therefore, by insulating the gate structures 84A and 84Busing the gate dielectric materials 81 and 81′, the present disclosureachieves a small fin-to-fin pitch of, e.g., about 46 nm, which was notachieved previously using existing manufacturing processing.

The small fin-to-fin pitch of the present disclosure allows for highintegration density and reduced device cost. The presently disclosedembodiment forms the insulation region (e.g., portions of the gatedielectric materials 81 and 81′) between gate structures 84A and 84B ina self-aligned manner, there is no need to form a cut pattern to cut agate structure that straddles the fins 64A/64B into two separate gatestructures. As the sizes of the cut patterns shrink in advanced processtechnology and approach the limit of photolithography techniques, it isincreasingly difficulty to accurately transfer the patterns of the photomask to the underlying photoresist. An improperly transferred cutpattern may cause bridge issue (e.g., electrical short) and results indevice failure. In addition, the minimum size of the cut patterns may belimited by the photolithography techniques, and the distance between thefins 64A and 64B may have to be made large to accommodate the size ofthe cut pattern. For example, the cut pattern may have a size of 20 nm,which is much larger than the 3 nm insulation region achieved by thepresent disclosure. Therefore, the present disclosure allows for ahigher integration densities not achieved by the previous processingmethods.

In addition, since there is no need to form a cut pattern then fill thecut pattern with dielectric material for insulation between gatestructures, the difficulty with filling high aspect ratio holes (e.g.,the cut pattern) is avoided. Furthermore, in processes where a metalgate is formed first then cut into two separate gates, the etchingprocess used in the cutting process may leave residues and/or may damagethe metal gates. The presently disclosed method avoids the metal gatecutting process, thus avoiding the damage to the metal gates andachieving better performance (e.g., smaller leakage current) for thesemiconductor device formed.

FIG. 21 illustrates additional processing following the step shown inFIGS. 19 and 20. In FIG. 21, a second ILD 95 is formed over the firstILD 90. Contact openings are formed through the second ILD 95 to exposethe gate structure 84A and 84B. Gate contacts 102, which include abarrier layer 104, a seed layer 109, and a conductive material 110, areformed in the contact openings and are electrically coupled to the gatestructures 84A and 84B.

In an embodiment, the second ILD 95 is a flowable film formed by aflowable CVD method. In some embodiments, the second ILD 95 is formed ofa dielectric material such as PSG, BSG, BPSG, USG, or the like, and maybe deposited by any suitable method, such as CVD and PECVD. The contactopenings may be formed using photolithography and etching. The materialsand the formation methods for the barrier layers 104, the seed layer 109and the conductive material 110 may be similar to those discussed abovefor the gate structures 84A/84B, thus details are not repeated.

Variations and modifications to the present disclosure are possible, andare fully intended to be included within the scope of the presentdisclosure. For example, one fin 64A is illustrated in the region 200and one fin 64B is illustrated in the region 300. However, more than onefins may be formed in each region (e.g., 200 or 300), and the gatestructure 84A and/or 84B may straddle more than one fins. As anotherexample, the disclosed method may also be used to form two gatestructures 84A and 84B that are of a same type, e.g., both gatestructures 84A and 84B may be gate structures of P-type transistors (orN-type transistors). As yet another example, the layer stack 81/83/85may comprise different materials from the layer stack 81′/83′/85′, e.g.,to form different gate dielectric materials 81 and 81′ for the PMOSregion and the NMOS region, respectively.

FIG. 22 illustrates a flow chart of a method of forming a gatedielectric material, in accordance with some embodiments. It should beunderstood that the embodiment method shown in FIG. 22 is merely anexample of many possible embodiment methods. One of ordinary skill inthe art would recognize many variations, alternatives, andmodifications. For example, various steps as illustrated in FIG. 22 maybe added, removed, replaced, rearranged and repeated.

Referring to FIG. 22, at step 1010, a first portion of a dummy gatestructure over a first fin is removed while a second portion of thedummy gate structure over a second fin remains, where removing the firstportion forms a first recess exposing the first fin. At step 1020, afirst gate dielectric material is formed in the first recess and overthe first fin. At step 1030, the second portion of the dummy gatestructure over the second fin is removed, where removing the secondportion forms a second recess exposing the second fin. At step 1040, asecond gate dielectric material is formed in the second recess and overthe second fin, the second gate dielectric material contacting the firstgate dielectric material. At step 1050, the first recess and the secondrecess are filled with a conductive material.

Embodiments may achieve advantages. For example, the disclosedembodiment obviates the need to from cut patterns to cut a metal gateinto separate metal gates. As a result, problems associated with formingcut patterns, such as bridge issue (e.g., electrical shorts), anddifficulty with filling high aspect ratio holes, are avoided. Inaddition, contamination or damage to the metal gate structures due tometal gate cutting is avoided, which results in better deviceperformance (e.g., smaller leakage current). The metal gate structuresformed using the present disclosed method are insulated by the gatedielectric material, thus the size of the gate structures and thefin-to-fin pitch can be much smaller than existing processing methods,which allows for higher integration density and lower manufacturingcost.

In an embodiment, a method includes removing a first portion of a dummygate structure over a first fin while keeping a second portion of thedummy gate structure over a second fin, where removing the first portionforms a first recess exposing the first fin; forming a first gatedielectric material in the first recess and over the first fin; andremoving the second portion of the dummy gate structure over the secondfin, where removing the second portion forms a second recess exposingthe second fin. The method further includes forming a second gatedielectric material in the second recess and over the second fin, thesecond gate dielectric material contacting the first gate dielectricmaterial; and filling the first recess and the second recess with aconductive material. In an embodiment, the second recess exposes atleast a portion of the first gate dielectric material. In an embodiment,forming the second gate dielectric material includes conformally formingthe second gate dielectric material in the second recess, where thesecond gate dielectric material contacts and extends along the portionof the first gate dielectric material exposed by the second recess. Inan embodiment, removing the first portion of the dummy gate structureincludes an anisotropic etch process, where removing the second portionof the dummy gate structure includes an isotropic etch process. In anembodiment, the anisotropic etch process is performed in a first etchingstep followed by a second etching step, wherein the first etching stepuses a different etchant from the second etching step. In an embodiment,the method further includes filling the first recess with a firstsacrificial material after forming the first gate dielectric materialand before removing the second portion of the dummy gate structure. Inan embodiment, the first sacrificial material includes a metal. In anembodiment, the method further includes filling the second recess with asecond sacrificial material after forming the second gate dielectricmaterial and before filling the first recess and the second recess witha conductive material. In an embodiment, the first sacrificial materialis a same material as the second sacrificial material. In an embodiment,the method further includes removing the first sacrificial material andthe second sacrificial material from the first recess and the secondrecess, respectively, before filling the first recess and the secondrecess with a conductive material. In an embodiment, the method furtherincludes performing a planarization process to remove top portions ofthe first sacrificial material and top portions of the secondsacrificial material before removing the first sacrificial material andthe second sacrificial material.

In an embodiment, a method of forming a Fin Field-Effect Transistor(FinFET) includes forming a first fin in a first region over asubstrate; forming a second fin in a second region over the substrate,the second fin being adjacent to the first fin; forming a first gatestructure over the first fin and the second fin; and removing a firstportion of the first gate structure in the first region to form a firstrecess. The method also includes forming a first gate dielectricmaterial lining sidewalls and a bottom of the first recess; depositing afirst material in the first recess and over the first gate dielectricmaterial; and removing a remaining portion of the first gate structurein the second region to form a second recess, the second recess exposinga first portion of the first gate dielectric material. The methodfurther includes forming a second gate dielectric material liningsidewalls and a bottom of the second recess; depositing a secondmaterial in the second recess and over the second gate dielectricmaterial; removing the first material and the second material from thefirst recess and the second recess, respectively; and filling the firstrecess and the second recess with a conductive material to form a firstgate electrode and a second gate electrode, respectively. In anembodiment, forming the second gate dielectric material includes forminga first portion of the second gate dielectric material along the firstportion of the first gate dielectric material exposed by the secondrecess. In an embodiment, depositing the second material includesdepositing the second material in the second recess and over the firstmaterial; and performing a planarization process to remove a top portionof the second material and to expose the first material. In anembodiment, forming the second gate dielectric material includes formingthe second gate dielectric material over the first gate dielectricmaterial, where after forming the second gate dielectric material, thefirst material is between the first gate dielectric material and thesecond gate dielectric material. In an embodiment, the first region is aP-type device region, and the second region is an N-type device region.

In an embodiment, a Fin Field-Effect Transistor (FinFET) device includesa first fin over a substrate; a second fin over the substrate andadjacent to the first fin; and a first gate structure over the firstfin, the first gate structure including a first gate dielectric layerover the first fin; and a first gate electrode over the first gatedielectric layer. The FinFET device also includes a second gatestructure over the second fin, the second gate structure including asecond gate dielectric layer over the second fin; and a second gateelectrode over the second gate dielectric layer, where a first portionof the first gate dielectric layer along a first sidewall of the firstgate electrode contacts a second portion of the second gate dielectriclayer along a second sidewall of the second gate electrode. In anembodiment, the first gate structure further includes a capping layerover the first gate dielectric layer; and a barrier layer over thecapping layer, where the barrier layer is between the first gateelectrode and the capping layer. In an embodiment, the capping layercomprises titanium nitride (TiN), and the barrier layer comprisestantalum nitride (TaN). In an embodiment, the first gate dielectriclayer and the second gate dielectric layer comprise a same dielectricmaterial, where the same dielectric material extends continuously fromthe first fin to the second fin.

In an embodiment, a method of forming Fin Field-Effect Transistor(FinFET) devices includes forming a dummy gate structure over a firstfin and over a second fin, where the dummy gate structure extendscontinuously from the first fin to the second fin and is surrounded by adielectric layer; performing a first removal process to remove a firstportion of the dummy gate structure over the first fin while masking asecond portion of the dummy gate structure over the second fin duringthe first removal process, where the first removal process forms a firstrecess in the dielectric layer; and forming a first gate dielectricmaterial in the first recess. The method also includes depositing afirst sacrificial material in the first recess and over the first gatedielectric material; performing a second removal process to remove thesecond portion of the dummy gate structure over the second fin, wherethe second removal process forms a second recess in the dielectriclayer; and forming a second gate dielectric material in the secondrecess. The method further includes depositing a second sacrificialmaterial in the second recess and over the second gate dielectricmaterial; removing the first sacrificial material and the secondsacrificial material; and filling the first recess and the second recesswith a conductive layer. In an embodiment, the first removal process isan anisotropic etch process, and the second removal process is anisotropic etch process. In an embodiment, the second recess exposes thefirst gate dielectric material. In an embodiment, the first sacrificialmaterial and the second sacrificial material comprise a same alloy.

In an embodiment, a Fin Field-Effect Transistor (FinFET) device includesa first fin above a substrate; a second fin above the substrate andadjacent to the first fin; and a first gate structure over the firstfin, the first gate structure including a first gate electrode; and afirst gate dielectric layer between the first gate electrode and thefirst fin. The FinFET device also includes a second gate structure overthe second fin, the second gate structure including a second gateelectrode; and a second gate dielectric layer between the second gateelectrode and the second fin, where the first gate electrode isseparated from the second gate electrode, where the first gatedielectric layer contacts the second gate dielectric layer. In anembodiment, the first gate dielectric layer has a first portionextending along a sidewall of the first gate electrode, and the secondgate dielectric layer has a first portion extending along a sidewall ofthe second gate electrode, where the first portion of the first gatedielectric layer contacts the first portion of the second gatedielectric layer. In an embodiment, the first portion of the first gatedielectric layer and the first portion of the second gate dielectriclayer have a same height measured along the sidewall of the first gateelectrode. In an embodiment, the first gate dielectric layer has asecond portion extending along an upper surface of an isolation regionbetween the first fin and the second fin, where the first portion of thefirst gate dielectric layer and the first portion of the second gatedielectric layer are substantially perpendicular to the second portionof the first gate dielectric layer.

In an embodiment, a Fin Field-Effect Transistor (FinFET) device includesa first fin and a second fin adjacent to the first fin; and a first gatestructure over the first fin and a second gate structure over the secondfin, where a first gate electrode of the first gate structure isseparated from a second gate electrode of the second gate structure byan insulation region, where the insulation region includes a portion ofa first gate dielectric layer of the first gate structure and a portionof a second gate dielectric layer of the second gate structure, wherethe first gate dielectric layer contacts the second gate dielectriclayer in the insulation region. In an embodiment, the FinFET devicefurther includes first source/drain regions over the first fin, thefirst source/drain regions doped with N-type impurities; and secondsource/drain regions over the second fin, the second source/drainregions doped with P-type impurities.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

1. A method comprising: removing a first portion of a dummy gatestructure over a first fin while keeping a second portion of the dummygate structure over a second fin, wherein removing the first portionforms a first recess exposing the first fin; forming a first gatedielectric material in the first recess and over the first fin; removingthe second portion of the dummy gate structure over the second fin,wherein removing the second portion forms a second recess exposing thesecond fin; forming a second gate dielectric material in the secondrecess and over the second fin, the second gate dielectric materialcontacting the first gate dielectric material; and filling the firstrecess and the second recess with a conductive material.
 2. The methodof claim 1, wherein the second recess exposes at least a portion of thefirst gate dielectric material.
 3. The method of claim 2, whereinforming the second gate dielectric material comprises conformallyforming the second gate dielectric material in the second recess,wherein the second gate dielectric material contacts and extends alongthe portion of the first gate dielectric material exposed by the secondrecess.
 4. The method of claim 1, wherein removing the first portion ofthe dummy gate structure comprises an anisotropic etch process, whereinremoving the second portion of the dummy gate structure comprises anisotropic etch process.
 5. The method of claim 4, wherein theanisotropic etch process is performed in a first etching step followedby a second etching step, wherein the first etching step uses adifferent etchant from the second etching step.
 6. The method of claim1, further comprising filling the first recess with a first sacrificialmaterial after forming the first gate dielectric material and beforeremoving the second portion of the dummy gate structure.
 7. The methodof claim 6, wherein the first sacrificial material comprises a metal. 8.The method of claim 6, further comprising filling the second recess witha second sacrificial material after forming the second gate dielectricmaterial and before filling the first recess and the second recess witha conductive material.
 9. The method of claim 8, wherein the firstsacrificial material is a same material as the second sacrificialmaterial.
 10. The method of claim 8, further comprising removing thefirst sacrificial material and the second sacrificial material from thefirst recess and the second recess, respectively, before filling thefirst recess and the second recess with a conductive material.
 11. Themethod of claim 10, further comprising performing a planarizationprocess to remove top portions of the first sacrificial material and topportions of the second sacrificial material before removing the firstsacrificial material and the second sacrificial material.
 12. A methodof forming a Fin Field-Effect Transistor (FinFET), the methodcomprising: forming a first fin in a first region over a substrate;forming a second fin in a second region over the substrate, the secondfin being adjacent to the first fin; forming a first gate structure overthe first fin and the second fin; removing a first portion of the firstgate structure in the first region to form a first recess; forming afirst gate dielectric material lining sidewalls and a bottom of thefirst recess; depositing a first material in the first recess and overthe first gate dielectric material; removing a remaining portion of thefirst gate structure in the second region to form a second recess, thesecond recess exposing a first portion of the first gate dielectricmaterial; forming a second gate dielectric material lining sidewalls anda bottom of the second recess; depositing a second material in thesecond recess and over the second gate dielectric material; removing thefirst material and the second material from the first recess and thesecond recess, respectively; and filling the first recess and the secondrecess with a conductive material to form a first gate electrode and asecond gate electrode, respectively.
 13. The method of claim 12, whereinforming the second gate dielectric material comprises forming a firstportion of the second gate dielectric material along the first portionof the first gate dielectric material exposed by the second recess. 14.The method of claim 12, wherein depositing the second materialcomprises: depositing the second material in the second recess and overthe first material; and performing a planarization process to remove atop portion of the second material and to expose the first material. 15.The method of claim 12, wherein forming the second gate dielectricmaterial comprises forming the second gate dielectric material over thefirst gate dielectric material, wherein after forming the second gatedielectric material, the first material is between the first gatedielectric material and the second gate dielectric material.
 16. Themethod of claim 12, wherein the first region is a P-type device region,and the second region is an N-type device region. 17.-20. (canceled) 21.A method of forming a Fin Field-Effect Transistor (FinFET), the methodcomprising: forming a first fin and a second fin adjacent to the firstfin; forming dummy gate structure over the first fin and over the secondfin; removing a first portion of the dummy gate structure disposed overthe first fin to form a first recess, the first recess exposing thefirst fin; forming a first gate dielectric material in the first recess;forming a first sacrificial material over the first gate dielectricmaterial in the first recess; removing a second portion of the dummygate structure disposed over the second fin to form a second recess, thesecond recess exposing the second fin and a sidewall portion of thefirst gate dielectric material; forming a second gate dielectricmaterial in the second recess, the second gate dielectric materialextending along and contacting the sidewall portion of the first gatedielectric material; forming a second sacrificial material over thesecond gate dielectric material in the second recess; and replacing thefirst sacrificial material and the second sacrificial material with ametal material.
 22. The method of claim 21, wherein removing the firstportion of the dummy gate structure is performed using an anisotropicetching process, and wherein removing the second portion of the dummygate structure is performed using an isotropic etching process.
 23. Themethod of claim 22, wherein the anisotropic etching process comprises afirst etching step using a first etching gas and a second etching stepusing a second etching gas different from the first etching gas.
 24. Themethod of claim 21, wherein the first sacrificial material and thesecond sacrificial material are formed of an alloy.